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AR# 38980

Description

When using a MicroBlaze AXI IC or DC interface with C_USE_DCACHE, C_USE_ICACHE ='0', or when C_ICACHE_ALWAYS_USED or C_DCACHE_ALWAYS_USED = 0 with cache disabled via software, there are no transactions from these ports. How do I resolve this issue?

Solution

MicroBlaze requires the cache logic to be included to use the AXI IC and DC interfaces, with the C_USE_DCACHE, C_USE_ICACHE parameters. Also, the respective cache must be enabled via software if the C_ICACHE_ALWAYS_USED or C_DCACHE_ALWAYS_USED = 0. When these parameters are set to '1', their respective interfaces will source transactions, even if the software cache is disabled.

This issue is improved in EDK 12.4 with MicroBlaze v8.00.b. In MicroBlaze v8.00.b the IC and DC interfaces will not be available in XPS when their respective C_USE_DCACHE or C_USE_ICACHE is not set to '1'. Note that this may cause existingEDK 12.3 designs to show the following error: ERROR:EDK:1599 - IPNAME:axi_interconnect INSTANCE:axi_interconnect_memory_mapped_0 - system.mhs line 27 - must have atleast 1 master assigned!

The solution is to enable the respective cache as documented above and reconnect the AXI interfaces.